The Helly Hansen Warm Mens Long Underwear Pants are lightweight with all the jacked up features of superior warmth, fine tuned comfort and functional perfection to flow with your every motion. These Helly Hansen Bottoms are your top level wool baselayer on the market. Combining the unique Lifa fiber technology next to skin to keep you dry, with a premium merino wool exterior, superior insulation and wicking properties, The Helly Hansen Long underwear Pants will be your one and only choice.